A dog walker found the cash floating in the South Drove Drain near Spalding on Oct. 25, The Independent reported Wednesday.
"It isn't everyday that an amount of money like this is found and somebody must have information that will help the police trace the lawful owner," Spalding police Detective Constable Steve Hull said. "I would be grateful to hear from people who have genuine information to pass on to me."
While much of the money was damaged, the rest appeared in fair condition, the newspaper said.
The Police Department, which is holding on to the money for now, plans to have the Bank of England help inspect the money and has been granted a court order to investigate where it came from.
If the owner can't be found, the money will become the subject of a further court forfeiture order, the newspaper said.